K<)N(iL. SV. VKT. AKADKMIKNS HAN DLINIJAU. BAND. 



26. 



n:() 



1, Nitzchie.i) 



Amiiliipnirii 



PIcurosiKiiia 

 Tropidoneis 



NaviniliH 

 sit't)riiies 



G. Frnstulia 



fu- 



NavicuhH mi- 

 crostisniatioiR 



Navi(.'ul» (le- 

 cipientes 



) Aiiipliii)rora (2) Anricula. 



\ Tropitloncis (4). 



j .. . . Dictyoiu'is .... Mastoneis. 



[ . . . . Scoliotropis .... Gomphoneis. 



1 . . . . I'leurosigina (3), Toxonidea. 



.... Naviculie Decussate . . . Anomoeoneis. 

 ) Naviculae fusiformes (5). 

 ) Naviculas iniorostigmaticfe (7). 



Navieuhe otliosticliie. 



(iyrosignia. 



Frnstulia ((i). 



(M.stula. 



Stenoneis. 

 j Amphipleura. 

 \ Brebissonia. 



Nav. minusculfe .... Microiieis. 



Nav. decipientes (8). 



Nev. punctata; (!)). 



Anorthoneis. 



Eucocconeis. 



Halainphora. 



Oxyaniphora. 



Amblyamphora. 



Psanimamphora. 



Nav. bacillarcs. 



Nav. entoleiiE. 



Nav. luesoleiae. 



.... Heteroneis. 



NaviculiB 

 punctatsB 



10. 



11. 



Nav. lineolattB (10). 

 Nav. lyratsB (12). 



Nav. heterosticbie .... Actiiioneis. 

 .... Acbiiantliidiuiii. 

 .... Disconcis. 

 Cymbclla. 



Naviculifi li- ) Gompboncnia, Rli()i(usph(niia. 

 neolatse j Tracbyneis. 



' Nav. laevistriatii! (11). 

 f Pinnularia. 

 [ ('yinbanipbora. 

 I Arcba^auiphora. 

 Navicular ly- ( Diploiicis (1.'5). 



Navicula; laj 

 vistriatse 



ratie 



13. Di])loneis 



14. 



Pseudo-ain 





j)biprora 



15. 





IG, 



Mastogloia 



\ Pseudo-amiibiprora (14). 



Anipbora .... Diplampliora 



Cyniatoneis. 



Scoliopleura. 



Nav. nicobaricai. 



Nav. luxuries*. 

 J Ualoneis .... Nciiliuni. 

 \ . . . . Calanipbora. 

 ( . . . . Acbnantbes . 



Plfui'oueis. 



\ . . . . Mastogloia. 

 ( Cocconeis. 

 \ Canipyloneis. 



Tropidoneis ooinpri.ses both symmetrioal not-winged and asymmetrical winged form.s. Tlie 

 foi'mer appear to be related to the Noricuhc niicrosfif/maticrf and Nav. fasiforincs. As asymmetrical 

 forms of the Nar. microstigmaticai are to be considered the following sections of the old genus Amphora: 

 0.n/(uiij)hnra, Anihiiininphora, Psaniinanip/tord ])rol)ably also Halampthora. Anortlioucis is ])robably 

 an asymmetrical form of Nar. tnicrostiymdticce. The Nav. miiiHscnla', of wliich Mirroncis and 

 Eucocconeis appear to comprise degenerating forms, are probably also allies of Nav. microstigmaticce _ 

 To the last named large section the Nav. <lcc/ij)icnfcs, Nar. eniolcice and Nav. mcsolcice are certainly 

 akin. Heteroneis may comprise degenerating forms allied to the same group. 



From the Nor. microstigmaticce the passage is gradual to the Nav. puncfatce and Nav. hetcro.^ticluc 

 and the former section is very closely connected with the Nav. Ujratcc. As degenerating forms are 

 perhaps to be regarded Disconcis and AchnunOiidium. Also some asymmetrical forms exist in 

 the section Nav. punctatce. Some Cymhellce represent very likely asymmetrical forms of Nar. 

 punctata'. 



The Nariculce Lgratcr are by intermediate forms connected with Diploneis. Akin to the 

 Nav. lyraice I also consider Pseudo-amphiprora. The new groups Amphora and Diplaniphora, 

 broken out from the old genus Amphora, may be regarded as asymmetrical forms of Diploneis. 



P.'ieudo-umphiprora is connected by intermediate forms with Caloncis, to which also Ncidium 

 seems to be allied. 



The Nar. lincoJafrc pass over to the group Punctatce by transitional forms, and the former 

 are also akin to Trachyncis (with the asymmetrical form Amphora Clcvci). A part of the Cymhellcc, 

 GompJionema, Phoicosphcnia and AmpJiora labucn-sis may be considered as asymmetrical forms of 

 the Nav. lineolatee. Degenerated forms of the Nav. lineolata' are probably to be found in Acfinoneis. 

 — On the other hand the Nar. lincolatfc are closely connected with the Nar. hcri.striaf/e, and those 

 with Pinnularia, ami 1 consider, with much hesitation, Cymhaniphora as asymmetrical forms of the 

 Nav. Icevistriatce. 



Kongl. Sv. Vet. Aknd. Handl. Hand 20. N:o 2. 2 



